Method for retaining insulators within tubes



Oct. 26, 1943. c. w. HANSELL METHOD FOR RETAINING INSULATORS WITHIN TUBES Filed. May 15, 1941 lNVENTOR alarm WIY 4255 ATLI'ORNEY Patented Oct. 26, 1943 METHOD FOR RETAINING INSULATORS WITHIN TUBES Clarence W. Hansell, Port Jefferson, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application May 15, 1941, Serial No. 393,682

Claims.

This invention relates to a new and improved method of fastening insulating spacers in concentric transmission lines.

An object of this invention is to provide a means for slightly deforming a tube at a pluralitypf radially widely spaced points from a single point on the outside of the tube or shielding conductor, and also to permit removal of the previously made deformation when it is required to remove the insulation spacers.

Another object of this-invention is to simultaneously' deform the tube from a single point by means of a clamp ring adjusted by an ordinary screw driver.

In the prior art, various methods and means for holding insulating discs which are used as spacers between the inner and outer conductors of a concentric line has been suggested. There has been a long felt need of retaining the insulating disc within the outer conductor by means of-a simple method which will require a minimum amount of work and without the use of complicated and expensive tools or equipment. Also, several prior art methods frequently gave rise to a corona discharge from the inner conductor, due to the retaining means presenting a. rough surface. A device employing a ring to clamp the insulators is disclosed in an application of L. L. Young, Serial No. 392,726, filed May 9, 1941. It is one of the objects of this invention to provide a method of holding the insulating disc in predetermined positions without marring the outside surface of theinner conductor, thus reducing the probability of corona discharge, also, this invention provides an outside surface of the inner conductor which is free from metallic clamping members, which has previously been used in some of the prior art construction. This will best be understood by referring to the accompanying drawing, in which:

Fig.1 is an end view of a clamp type of forming member of this invention;

Fig. 2' is a section of Fig. 1, the section being 1 taken on line A-A thereof;

Fig. 3 is a section showing the clamp of this invention applied to the outer conductor of a Y concentric line;

Fig. 4 is another section of the clamp of this invention in which the gripping members have been shifted approximately 60 with respect to Fig. 3; and

Fig. 5 is a longitudinal section, showing insulating spacers disposed within an outer conduc-- the band and as'shown are preferably placed 120 apart. The wedge-like clamping members are made thicker at the ends than at the center and may be secured to the band I and disposed with their lengths transverse or cross-wise to the band, by any suitable means, such as by soldering, welding, etc. The lower portion of band I is provided with extension ears 3 and l which are so bent that a space 5 is provided. The ears 3 and 4 have apertures located therein for clamping screws 6 and nuts I.

Referring now to Figs. 3 and 4, the operation of the clamping device of this invention is as follows: The insulating discs 8 are spaced at predetermined points along the outer surface of the inner conductor 9 over which is placed an outer conductor I 0. The completely assembled clamping device of this invention is next placed over the outer conductor in a, position so that the three wedge-like pieces 2 have their centers substantially over the centers of the spacers 8.

'The ends 3 and 4 of band I are tightly drawn together by means of bolts 6 and as is shown in Figs. 3 and 5, the wedges 2 will then deform the outer conductor slightly by forming a curved indentation as shown at a point II in three places approximately spaced 120 apart, so that the insulating disc 8 will be held securely in place by operative engagement. Disc 8 is made only slightly smaller than the inside diameter of tube III. The disc 8 is the ordinary form of insulating spacer having an aperture of the proper size for the inner conductor 9. It is composed of material having low dielectric loss at the ultra high frequencies. The inner diameter is made slightly larger than the outside of the inner conductor. The outside diameter is made but slightly smaller than the inside diameter of the outer conductor [0, and for ease in assembly, the edges are rounded over slightly. If, at a future time, repairs are necessary and the outer conductor has become permanently distorted, so that the disc is still tightly held tothe outer conductor III, and should it be desired to remove the disc, the previous distortion may be relieved and the disc loosened if the band I is rotated approximately and slightly re-tightened, as'shown in Fig. This operation will again place the tube in its normal true diameter.

This invention should not be limited to the precise arrangement shown.

What is claimed is:

1. The method of fastening insulators for a concentric transmission line within a metal tube including the steps of placing said insulators at predetermined positions within said tube and spacing said insulators apart from one another, applying pressure at a plurality of radial spaced points on the outside of said tube adjacent said insulators to slightly distort the normal diameter of. said tube to grip and retain said insulators thereto.

2. The method of fastening an insulator for a high frequency concentric transmission line within a metal tube including the steps of placing said insulator at a predetermined position within said tube, applying pressure at a plurality of radial spaced points on the outside of said tube adjacent said insulator and forming slightly curved portions to distort the normal diameter of said tube to grip and retain said insulator thereto.

3. The method of fastening insulators for a concentric transmission line within a metal tube including the steps of placing said insulators at predetermined positions within said tube and spacing said insulators apart from one another, slightly applying pressure at a plurality of radial spaced points on the outside of said tube adjacent and on each side of said insulators to slightly distort the normal diameter of said tube to grip and retain said insulators thereto.

4. The method of fastening insulators for a high frequency concentric transmission line within a metal tube including the steps of placing said insulators at predetermined positions within said tube, slightly applying pressure at a plurality of radial spaced points on the outside of said tube adjacent said insulators to slightly distort the normal diameter of said tube at each side of said insulator to grip and retain said insulators thereto.

' 5. The method of non-permanent fastening of insulators for a concentric transmission line within a metal tube, including the steps of placing said insulators at predetermined positions within said tube and spacing said insulators apart from one another, applying pressure at three radially spaced points apart on the outside of said tube adjacent said insulators to slightly distort the normal diameter of said tube to grip and retain said insulators thereto, and to. permit release of said insulators by applying pressure at three spaced points which are intermediate said first mentioned spaced points.

' CLARENCE W. HANSELL. 

